Signaling system.



F. M. SLOUGH.

SIGNALING SYSTEM.

APPLICATION FILED MAY 8. 1914.

LQWAEQQ Patented May 28,1913,

R/NGING GENEEATGIFS fif i j y ww outrun srrarns "rad ant canton.

FRANK M. SLOUGH, OF ELYRIA, OHIO, ASSIGNOR TO THE GARFORD MANUFACTURING COMPANY, OF ELYRIA, OHIO, A. CORPORATION OF OHIO.

SIGNALING SYSTEM.

Specification of Letters Patent.

Patented May 28, 1918.

To all whom it may concern Be it known that I, FRANK M. SLoUGH, a citizen of the United States, and a resident of Elyria, in the county of Lorain and State of Ohio, have invented certain new and useful Improvements in Signaling Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to selective party line signaling systems in which the signal devices at the substations employ reed tongues having natural rates of vibration differing from each other, and which are adapted to be selectively operated by alterhating currents of dilferent frequencies. Systems of this type find their greatest use with telephone systems where bells or ringers are used at the substations.

In systems of this type hitherto in use, so far as I am aware, it has been the prac tice, and necessary, to produce the best results, not only to vary the frequency but to vary the voltages of the impressed currents, the current of the highest'frequency being of the highest voltage. This arrangement has caused considerable inconvenience for several reasons. It is necessary to increase the insulation and other protection of the whole system over and above that which would otherwise be employed with voltages used to operate the ordinary or straight line ringers. This additional protection is not only expensive in the installation, but is more expensive and more ditficult to maintain than would be true if lower voltages could be employed.

The high voltages are a constant source of danger to people working with or using the system. This is especially true if an operator inadvertently rin s upon a line already in use, as a subscri er rung in the ear frequently results in a personal injury suit against the operating company. In fact, special means have been provided to prevent this contingency happening.

Others have made elforts to produce a system in which currents of low and uniform voltages may be employed by the introduction of condensers of different capacities, but so far as I am aware, none of these elforts' have met with complete success, and it is a well known fact that graduated voltages have been employed in practically all commercial systems of the type mentioned now in use.

Another particular object of my invention is to produce a low voltage signaling system of the class described, and at the same time employ apparatus uniform, or substantially uniform in character at each substation, thus realizing great convenience both in manufacturing and operating.

Other objects of my invention and the invention itself will probably be better understood from a description of an embodiment of the invention.

The figure on the drawing illustrates an embodiment of my invention, the circuit and much of the apparatus being shown in diagram and other parts in perspective.

Referring now to the embodiment illustrated in the drawing, at A I show apparatus which is used at a main or central station. Telephone lines are illustrated at X and Y, extending by their limbs 1 and 2, and 3 and 4:, the line X, to substations B, O, D and E. I have illustrated this line as provided with four substations, though any suitable number may be employed. On the line Y I show a single substation l3, though likewise any suitable number may be employed. The lines terminate at the central station preferably upon a switchboard, and

in means which enable the lines to be con nected together, suchas jacks J and J. At the central station means are provided for uniting the lines, such as a cord circuit H, which terminates in plugs P and I adapted to be inserted into the jacks of the line in the well known manner for the purpose of connecting the lines together through the cord circuit.

The cord circuit is provided with suitable supervisory signaling apparatus, and the line circuits with suitable line signaling apparatus, all of which constitutes no part of my invention and will not be described in detail. The substations may be provided with telephone sets T, T T T T which are also old and constitute in themselves no part of my invention. These telephone sets are best connected in bridge of the line, and as illustrated, are in bridges which are normally open. Each substation is pro-vided with a signaling device, such as aringer, illustrated at R, R R R R The ringers at the stations on the line X are substantially alike, differing only in such features as are necessary to mechanically tune them differently. In the form shown this is effected by changing the-size of the weights or tappers 5.

The ringer R being illustrated in a more detailed manner than the others, a description of this will be sufiicient. The ringer is provided with electromagnet windings, preferably in two coils illustrated at 6. These coils are mounted upon a core 7, here shown Y which the tapperb strikes. The tapper 5'is mounted upon a support, such asa rod v15. The armature'is shown at 16 connected to one end of the reed. R is here illustrated as the'low frequency ringer, the frequency increasing to the left, though, of course, the ringers may be arranged in any suitable manner. 7

To secure the results of my invention, the ringers are connected in bridges 17 of the line, which are normally closed, and condensers 18, 19, 20 and 21 are connected, one in each said bridges. These condense ers are of substantially uniform capacity. They may be of like construction. At the main station I provide means for supplying the operating currents, here illustrated as a plurality of generators 22, 23, 24 and v 25, each adapted to be connected in circuit with a telephone line and each adapted to produce alternating currents of low voltage and each substantially alike in voltage, though different in frequency. I have illustrated a battery of generators merely for convenience, as it will be apparent that any suitable current producing means may be employed. Indeed, the provision of means whereby currents of uniform voltages may be employed greatly broadens the field of current producing means from which selections may be made.

The frequencies produced by the current producing means are such as the bells on the lines are tuned for, and to which they selectively respond, one bell to each frequency, while the other ringers are not d.is turbed. Suitable means are provided to connect the current producing means to the signaling line. I have here-shown a plurality ofkeys 30, 31, 32 and 33 for connecting any one of the generators to the terminal of the cord circuit through which they are c'onnected to the line. When it is desired to selectively signal one of the stations upon the line X, for example, the station at E, one operates one of the ringing keys say the key v30, which controls the connection of the generator adapted to produce a current to which the ringer R responds. Alternating current is then placed upon the line X by the generator 22, and the ringer R alone being tuned to respond when that frequency of alternating current is applied, responds to the same, the other ringers remaining silent. V

Particular objects of my invention are to provide a system employing apparatus of such a character and in such an arrangement that uniform voltages may be employed, in which these voltages may be so low as to fall within the limits to which telephone apparatus in general is employed, thus making it unnecessary to make any special arrangements when selective lines are employed, and in which apparatus either entirely or substantially uniform in character may be employed at the difierent stations, excepting, of course, the special mechanical tuning means employed in the ringers. These aims are best'accomplished byincreasing the efliciency of the individual ringers,

which may be done by laminating parts of the magnetic circuit of the signaling devices, and in other ways. My invention is not limited to any particular means for accomplishing this, though it is realized to a high degree by laminating. It is entirely practical to apply it to systems employing ringers such as are already maunfactured and used.

Hitherto in the systems using condensers of substantially the same characteristics, so far as I am aware, the bell bridges at the substations have not been made resonant for the highest frequency current (a very desirable thing, as will be explained) because with the high voltages used with such currents, the lower frequency bells would tap or otherwise misbehave when the high frequency high voltage current was placed upon the line. This is especially true when apparatus uniform in character'is employed, 7

since then all the bridges will be resonant for the highest frequency currents. Now,

it is desirable to make all of the bridges resonant for the high frequency current, because it increases the sensitiveness of the high frequency. bell, which is hardest to operate, and enables apparatus uniform in character to be employed at the various substations. By the means which I-have described, I am enabled to employ a low voltage which will not cause the lower frequency bells to misbehave when their bridges are attuned electrically to the highest frequencycurrents.

My invention is made more feasible by increasing the efficiency of-the high frequency ringer and otherwise making it of such a character that it is easier to effectively electrically attune the bridge in which it is connected. This may be accomplished in one way by laminating the portions of the magnetic circuit of the ringer, as I have illustrated. When this is done, I find the eddy currents, which are more particularly pronounced on the high frequency bell, are practically eliminated, so that it is possible to attain the same effect with a low voltage high frequency current, in a Way which would otherwise be accomplished only by using a high voltage.

This particular embodiment of my invention, including the details thereof, have been illustrated for the purpose of describing the invention, and notthat I wish to be limited thereto. I contemplate numerous and extensive departures from the details of the invention, which is more particularly described in the appended claims.

I claim:

1. In a selective reed signaling system, the combination of a main station, a plurality of substations and a signaling line connecting said stations, a bridge at each substation including a reed signaling device, said signaling devices being provided with parts o determine the mechani al tuning of t same, said parts being different for the different signaling devices, the other parts of the signaling devices being substantially the same for each signaling device, condensers connected in said bridges in series with the signaling devices, the capacity of the con clensers being such that the bridges are approximately electrically attuned for the highest frequency current employed, said condensers being of substantially the same capacity, a plurality of generators at the main station adapted to produce currents of substantially the same voltage but of different frequencies, and each of a frequency to which one of the signaling devices is mechanically tuned to respond, and means to connect the generators to the signaling line.

2. In a selective reed signaling system, the combination of a main station and a plurality of substations, a signaling line connecting said stations, a bridge of the signaling line at each of the substations, a reed signaling device connected in each of said bridges. certain parts of said devices being different to determine the mechanical tuning of the devices, the other parts of the devices being the same in construction. and mode of operation, a condenser connected in each bridge in series with the signaling devices, such condensers being of the same capacity and of such a capacity that the bridges are electrically attuned for the highest fre quency currents employed, a plurality of generators at the main station for producing currents of the same voltage but of different frequency, each of a frequency for which one of the signaling devices at the substations is tuned to respond, and means to connect the generators to the signaling line.

,3. In a selective reed signaling system, the combination of a main station and a plurality of substations, signaling line connecting said stations, a bridge of the signaling line at each of the substations, a reed signaling device connected in each of said bridges, certain parts of said devices being different to determine the mechanical tuning of the devices, the other parts of the devices being the same in construction and mode of operation, a condenser connected in each bridge in series with the signaling devices, such condensers being of the same capacity and of such a capacity that the bridges are electrically attuned for the highest frequency currents employed, means at the main station for producing currents of the same voltage but of difierent frequencies and means for connecting said current producing means to the signaling line.

4. In a selective reed signaling system, the combination of a main station, a plurality of substations, and a signaling line connecting said stations, bridges at the substations including reed signaling devices of substantially the same construction and characteristics except as to the tune determining parts, condensers connected in said bridges in series with the signaling devices, all of said bridges being electrically tuned for the highest frequency current employed, and means at the main station for throwing upon the signaling line currents of substantially the same voltage but of different frequencies, the frequencies of the currents corresponding to those for which the signaling devices are adapted to respond.

5. In a selective reed signaling system, the combination of a main station, a plurality of substations, and a signaling line connecting said stations, a bridge at each substation including a reed signaling device, said signaling device being provided with parts to determine the mechanical tuning of the same, said parts being different for the different signaling devices, the other parts of the signaling devices being substantially the same for each signaling device, condensers connected in said bridges in series with the signaling devices, said bridges being tuned for the highest frequency current employed for signaling purposes, and means at the main station for producing and throwing upon the line currents of different frequencies but of substantially the same voltage, the frequency of the currents produced thereby being those for which the signaling devices are adapted to selectively respond.

6. In a party line reed selective'signaling system, the combination of a main station and a plurality of substations, a signaling line connecting the same, bridges of said line at the substations, mechanically tuned signaling devices in said bridge, apparatus at the main station for producing and throwing upon the line currents of different frequencies for selectively signaling the signaling devices at the substations, the currents produced by said apparatus being of substantially the same voltage, and means for electrically attuning all of said bridges to be in resonance with the current of highest frequency.

7. In a selective reed party line system, the combination of a main station, a signaling line connected to said main station, a plurality of substations on said signaling line, bridges of the line at the substations, mechanically tuned reed signaling devices in said bridges, generating apparatus at the main station for generating currents of substantially the same voltage but of different frequency, and means including the signaling devices for electrically attuning the substation bridges to be in resonance to the highest frequency current.

8. The method of selectively signaling,in which a plurality of differently tuned reed signals are connected across a telephone line, which consists in electrically attuning said (20pm of thla patent may be obtained for bridges for resonance with the highest frequency current employed, and using uniform voltage variable frequency currents for selecting and operating said signals. 7

9. The method of selectively operating differently tuned signals, arranged in bridge of a telephone line which consists in electrically attuning said bridges uniformly to be in resonance with the highest frequency current used and selectively operating said signals by the application of various frequency currents to the telephone line.

10. The method of selecting and operating differently tuned signals, bridged to a telephone line, which consists inelectrically attuningeach bridge to be in resonance with the current employed to operate the highest frequency ringer and applying to said line one of a plurality of different frequency currents of the same voltage, each of said currents being in synchronism with one of the signals on the line.

In witness whereof, I have signed my name in the presence of two witnesses this 4th day of May, 1914.

V FRANK M. SLOUGH.

Witnesses:

JOHN S. Riomnr, META M. SMITHBERGER.

five cents each, by addressing the Gommissioner of Patents.

Washington, D. (2. 

